The present invention relates to an automobile air-conditioning apparatus with air blower control for air-conditioning the interior passenger compartment of an automobile, and more particularly to an automobile air-conditioning apparatus with air blower control for optimizing control of the amount of air fed from an air blower when the compartment starts to be cooled.
Automobile air-conditioning apparatus has heretofore been employed to air-condition an automobile passenger compartment and also prevent the front windshield from getting fogged for thereby giving the driver clear visibility through the front windshield to allow the driver to drive the automobile with safety. In automobile air-conditioning apparatus, a voltage to be applied to an air blower motor is computed or found from a memory table according to a predetermined control pattern related to the difference between a detected compartment temperature and a preset compartment air temperature and based on the air temperature at an evaporator outlet, the amount of sunlight applied to the compartment, the ambient air temperature, etc. The determined motor voltage is then applied to the air blower motor for controlling the rate of air flow from the air blower.
When starting to cool the compartment, a large amount of hot air may be discharged into the compartment since the evaporator is not yet sufficiently cooled, or a bad odor may be produced due to contamination of the evaporator. To prevent such problems, it has been customary to provide an air blower driver circuit composed of the air blower motor, an air flow rate selector switch, and an air flow rate limiting resistor which are connected in series, with a breeze control unit composed of a resistor and a relay contact of a relay having a normally closed contact, the resistor and the relay contact being connected parallel to each other. When the air blower starts to be operated, the relay coil of the relay is energized for a certain period of time by a timer, so that the amount of air discharged by the air blower is limited to a breeze level over a period of time preset by the timer after the compartment has started being cooled.
Instead of relying upon time control by the timer, either an air temperature sensor disposed in the vicinity of the evaporator or an air temperature sensor disposed in the vicinity of the heater core may be used, and the amount of air flow from the air blower may be progressively increased until the air temperature detected by the selected sensor reaches a preset temperature.
According to the above control operation, hot air is prevented from entering the compartment when the compartment starts to be cooled.
With the aforesaid conventional air blower control; air is supplied at a breeze level for a constant period of time or until a single detected air temperature reaches a preset temperature. The amount of air may not be controlled at an appropriate level, however, if an ambient air temperature sensor is significantly affected by the heat of the engine while the automobile is at rest, at the time of restarting the engine when the compartment air temperature is substantially optimum and less than a substantial amount of cool air is required. For example, when the engine is restarted 10 to 20 minutes after it has been stopped, heat radiated by the engine is applied to the ambient air temperature sensor which is normally located on the back of the bumper near the engine, thereby increasing the temperature detected by the ambient air temperature sensor. As a result, the amount of air discharged into the cabin is undesirably increased, making the passengers uncomfortable.